Patent NZ-604337-A (NZ)
Title: Amphiphilic polysiloxane prepolymers and uses thereof
Inventor: CHANG FRANK
IPC: G02C7/04
Filed: 2011-07-29
Abstract: 604337 Disclosed is an amphiphilic branched prepolymer, comprising: from about 5% to about 75% by weight of hydrophilic monomeric units derived from at least one hydrophilic vinylic monomer; from about 1 % to about 85% by weight of polysiloxane crosslinking units derived from at least one polysiloxane crosslinker having two or more terminal ethylenically unsaturated groups; from about 2% to about 48% by weight of dangling polysiloxane chains each of which is terminated with an ethylenically unsaturated group; and from about 0.25% to about 5% by weight of chain-transfer units derived from a chain transfer agent other than a RAFT agent; wherein the amphiphilic branched prepolymer is obtained by (i) polymerizing a polymerisable composition to obtain an amphiphilic branched polysiloxane copolymer, wherein the polymerisable composition comprises (a) from about 10% to about 94% by weight of a partially ethylenically functionalized polysiloxane, wherein the partially ethylenically-functionalized polysiloxane is a mixture of reaction products obtained by reacting a first ethylenically functionalising vinylic monomer having a first reactive functional group with a functional polysiloxane compound having two or more second reactive functional groups at a molar equivalent ratio, REquivalent, of from about 40% to about 95%, wherein each first reactive functional group reacts with one second reactive functional group in the presence or absence of a coupling agent to form a covalent bond or linkage, wherein the mixture of reaction product comprises at least one polysiloxane crosslinker having at least two ethylenically unsaturated groups and at least one polysiloxane vinylic monomer or macromer having at least one second reactive functional group and at least one ethylenically unsaturated group, (b) at least one hydrophilic vinylic monomer, (c) optionally a hydrophobic vinylic monomer, (d) a chain transfer agent other than a RAFT agent, wherein the chain transfer agent optionally includes a third reactive functional group, and (e) a free-radical initiator, and (ii) ethylenically functionalizing the amphiphilic branched polysiloxane copolymer by reacting it with a second ethylenically functionalizing vinylic monomer having a fourth reactive functional group which reacts with one second or third reactive functional group in the presence or absence of a coupling agent to form a covalent linkage, thereby forming the amphiphilic branched polysiloxane prepolymer. Also disclosed is a method for making silicone hydrogel contact lenses, comprising the steps of: (i) obtaining an amphiphilic branched polysiloxane prepolymer as defined above; (ii) using the amphiphilic branched polysiloxane prepolymer to prepare a lens-forming composition which comprises (a) from about 60% to about 99% by weight of the amphiphilic branched polysiloxane prepolymer, (b) from about 0.1 % to about 5% by weight of a free-radical initiator, and (c) from 0 to about 20% by weight of at least one polymerisable component selected from the group consisting of a hydrophilic vinylic monomer, a silicone containing vinylic monomer, a silicone-containing vinylic macromer with one sole ethylenically-unsaturated group, a hydrophobic vinylic monomer, a linear polysiloxane crosslinker terminated with two ethylenically-unsaturated groups, a crosslinking agent having a molecular weight of less than 700 Daltons, a polymerisable UV-absorbing agent, and mixtures thereof; wherein the percentages by weight of components (a)-(c) are relative to the total amount of all polymerisable components (including those not listed above) in the lens-forming composition; (iii) introducing the lens-forming composition into a mould, wherein the mold has a first mould half with a first moulding surface defining the anterior surface of a contact lens